Drop in Ebola cases may thwart drug and vaccine trials

WE MAY have lost a historic chance to test drugs and vaccines against the Ebola virus, which could leave us without the weapons to prevent the next outbreak.

The epidemic in West Africa prompted an unprecedented rush of clinical trials. But some are now being abandoned and others may produce few clear results, because the steep fall in the number of Ebola cases makes it difficult to test whether the drugs work in enough cases for statistically valid trials.

The fall in cases means the epidemic is entering a new, difficult phase. Last week, the number of people with Ebola rebounded across the affected region for the first time this year, possibly because controls were relaxed too soon. Until every last case is contained, the UN warns that another massive flare-up is a real risk.

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No one is complaining that last year’s exponential rise in Ebola cases did not continue. David Fisman of the University of Toronto, Canada, says something slowed disease transmission in November, possibly ordinary people taking more precautions. Factoring that into epidemic models “nicely predicts” what is happening now, he says. “We think the epidemic is peaking now, or peaked in mid-January. We project around 35,000 reported cases in total” – far short of the million feared in September.

Lack of numbers could also stymie vaccine giants Merck and GlaxoSmithKline, which last week started giving one of their two experimental Ebola vaccines or a control vaccine to 30,000 volunteers – who will then be watched for Ebola. The decline in cases means the trial may never reach a conclusion, says GSK spokeswoman Aoife Pauley.

The irony of defeating Ebola just in time to prevent tests that could stop the next epidemic is not lost on researchers. The trials were designed and approved in months rather than the years it usually takes – but that’s still not soon enough, says Jake Dunning of Imperial College London, who hopes to launch a trial of an RNA-based anti-Ebola drug in Sierra Leone next week.

We may be left with aborted trials and scattered observations of the handful of drugs that have been tried on patients, he says – and they cannot prove whether any treatment will protect us when Ebola explodes again.

This article appeared in print under the headline “Ebola’s retreat thwarts drug and vaccine trials”